The present invention relates to a method for manufacturing a semiconductor device using an immersion lithography process.
In order to manufacture semiconductor devices that have been smaller, patterns have also become smaller. In exposers, although KrF (248 nm) or ArF (193 nm) as an exposure light source have been applied to an exposure process, attempts have been made to use short wavelength light sources such as F2 (157 nm) or EUV (13 nm) to increase numerical apertures (NA).
However, when new light sources such as F2 are applied, a new exposer is required, which results in increasing manufacturing costs. Also, the increase of numerical apertures degrades a focus depth width.
Recently, an immersion lithography process has been developed in order to solve these problems. While an existing exposure process utilizes air having a refractive index of 1.0 as a medium of exposure beams between substrates having a photoresist film and an exposure lens of an exposer, the immersion lithography process utilizes a solution such as H2O or an organic solvent having a refractive index of more than 1.0 as a medium of exposure beams. As a result, although exposer light sources having the same wavelength are used, the same effect is obtained as when a light source of a shorter wavelength is used or a lens having high numerical apertures is used, without degradation of the depth of focus.
The immersion lithography process improves the depth of focus. Moreover, fine patterns of less than 60 nm can be formed with the existing exposure light sources.